Typically, a magnetic head used in a magnetic disk drive is provided with a playback head for reading information recorded on a recording medium. In the playback head, a magnetoresistive effect film changes resistance in response to a magnetization signal recorded on the recording medium.
The magnetoresistive effect film is typically provided with a magnetically pinned layer for pinning a direction of magnetization in one direction and a free magnetic layer which freely changes a direction of magnetization depending on a signal magnetic field from the medium, and detects the change in the magnetoresistance produced by changing the relative angle of the respective directions of magnetization of the free magnetic layer and the magnetically pinned layer by the action of the magnetization signal of the medium, and also reads the signal. Consequently, in order to improve the reading performance of the playback head, a magnetoresistive effect film exhibiting a large change in the magnetoresistive effect and a magnetoresistive effect element provided with the film are very useful.